1. Field of the Invention
This invention generally relates to a friction clutch for a transmission of a motor vehicle, wherein the friction clutch has a clutch plate. In addition, the invention also more specifically relates to a torsional vibration damper and a clutch plate for a friction clutch.
In general, a friction clutch for a transmission of a motor vehicle can have a hub which defines an axis of rotation, which hub can receive a drive shaft of a transmission therein. About the hub, and concentric to the axis of rotation, there can be a hub disc. In addition, cover plates can be located on both sides of the hub disc and can be firmly and non-rotationally connected to one another and held at a distance from one another.
At least one of the cover plates, in a radially outward location, can have friction linings. Coil springs for the load range of the friction clutch can be disposed in apertures in the hub disc on one hand, and in the lining support and cover plate on the other hand. Such an arrangement can also include a friction device between the hub disc and cover plates, which friction device can include load friction discs located on both sides of the hub disc. The coil springs can preferably be in contact, on one end thereof, with control edges of the apertures of the lining support and cover plates, while at the other end can be in contact with stop tabs of the load friction discs. At least one of the friction discs can be a ring-shaped base body having webs to hold the stop tabs.
2. Background Information
Federal Republic of Germany Laid Open Patent Application No. 40 28 616 A1 discloses a known clutch plate on which there are two load friction discs, with one disc being located on either side of the hub disc. During the idle phase, one of these load friction discs follows the driving-side clutch elements, such as the lining supports, or the cover plate in a friction-tight fashion. This load friction disc has stop tabs. Each of the stop tabs can be engaged between a spring provided for load operation, and a control edge of an aperture corresponding to the spring. During load operations, the stop tabs can be brought into contact, via the spring, against this control edge. On account of the non-rotational connection of one load friction disc with the other friction disc, these friction discs participate in the motion of the hub and execute a relative movement with respect to the driving-side clutch elements. Since one of the load friction discs is pressurized, with a friction force, by a spring acting in the axial direction, and this axial application of force is transmitted to the other load friction disc, the two load friction discs produce a friction force which is effective during load operation.
When a stop tab encounters the corresponding control edge, the stop tab must generally absorb a force on both active surfaces thereof. This is essentially due to the pressure which is being applied to the stop tabs, on its opposite side away from the control edge, by the spring located in the corresponding aperture. Since, during load operation, the load friction disc participates in the motion of the hub disc and tends to follow any wobbling motion of the hub disc, the stop tabs can be moved into a position relative to the control edge in which the forces applied to the active surfaces of the stop tabs are transmitted, with different lever arms, to the web connecting the stop tabs to the remaining part of the load friction disc. The result can be a torque which acts on the stop tabs, and which leads to the accumulation of stresses in the above-mentioned web. These stresses can be sufficiently high to thereby result in a rupture in the vicinity of the web. To prevent such a rupture, the stop tabs on such load friction discs are conventionally subjected to a heat treatment to increase their strength. However, such a heat treatment can be complex, time-consuming and expensive.